The optically active β-trifluoromethyl-β-hydroxycarbonyl compound which is an objective compound of the invention is an important intermediate for medicaments and agricultural chemicals.
As processes for producing an optically active β-trifluoromethyl-β-hydroxycarbonyl compound, biological methods and chemical methods have been reported.
As the biological methods, there are known (1) a process of asymmetric reduction of a trifluoromethyl ketone compound by bread yeast (see Non-Patent Document 1) and (2) a process of optical resolution of a racemic derivative by an enzyme (see Non-Patent Document 2).
Moreover, as the chemical methods, there are known (3) a process of reacting fluoral gas with various nucleophiles in the presence of an asymmetric catalyst comprising an asymmetric ligand and a transition metal complex (see Non-Patent Documents 3, 4 and 5) and (4) a process of reacting fluoral ethyl hemiacetal with a chiral imine (see Patent Document 1).
On the other hand, a process of reacting various aldehydes with acetone in the presence of optically active proline has been already reported (see Non-Patent Document 6), but there has been no report on an example of using a hydrate (geminal-diol) or hemiacetal of an aldehyde, both of which are stable as electrophiles, especially a hydrate or hemiacetal of fluoral.                Patent Document 1: JP 2001-226308 A        Non-Patent Document 1: Tetrahedron, (England), 1994, Vol. 50, pp. 11995–20000        Non-Patent Document 2: Journal of Organic Chemistry, (USA), 1987, Vol. 52, pp. 3211–3217        Non-Patent Document 3: Organic Letters, (USA), 1999, Vol. 1, pp. 2013–2016        Non-Patent Document 4: Journal of Fluorine Chemistry, (Netherlands), 1999, Vol. 97, pp. 51–55        Non-Patent Document 5: Tetrahedron, (England), 1996, Vol. 52, pp. 85–98        Non-Patent Document 6: Journal of American Chemical Society, (USA), 2000, Vol. 122, pp. 2395–2396        
In the processes described in Non-Patent Documents 1 and 2, it is necessary to construct the carbon skeleton beforehand because the processes comprise asymmetric reduction or optical resolution. In the latter case, yields have not ever exceeded 50%.
The processes described in Non-Patent Documents 3, 4 and 5 are effective since construction of the carbon skeleton and asymmetric induction can be effected simultaneously in the presence of a catalytic amount of the asymmetric catalyst. However, the processes are not satisfactory as industrial production processes since the asymmetric catalyst used therein is relatively expensive and the processes use fluoral gas which is considerably liable to polymerize.
On the other hand, the process described in Patent Document 1 is suitable as an industrial production process since stable ethyl hemiacetal of fluoral can be employed. However, the process requires an equivalent amount of a relatively expensive chiral auxiliary group and also it involves a vexatious step of synthesizing a chiral amine beforehand.
Thus, it is strongly desired to develop a process capable of producing an optically active β-trifluoromethyl-β-hydroxycarbonyl compound, which is industrially applicable.